Loud speaker system

ABSTRACT

A loud speaker is installed on the rear plane of a baffle board facing an opening within the baffle board which opening in cross section takes the form of a narrow forwardly directed cone and an annular acoustic resistance member which is triangular shaped in section is fixed to the cutting plane of the opening. Alternatively, a ring member which narrows in a forward direction to form a forwardly narrowing cone in cross section is fixed to the front of a loud speaker flange and fits within a baffle board opening with the flange installed on the rear plane of the baffle board. An annular acoustic resistance member of triangular cross section is fixed to the inside surface of the forwardly narrowing ring or to the front surface of the loud speaker flange internally of the ring.

United States Patent '1 I Kinoshita et ,1.

[54] LOUD SPEAKER SYSTEM [72 Inventors: Shouzo Kinoshita, Tokorozawa;lsao Yamamura, Tokyo, both of Japan [731 Assignee: Pioneer ElectronicCorporation, To-

kyo,.lap'an [22] Filed: Sept. 28, 1971 {21] Appl.No.: 184,404

[30] Foreign Application Priority Data 51 Sept. 26, 1972 3,067,834l2/l962 May 18l/31B Primary Examiner-Stephen J. Tomsky Att0rney-Sughrue,Rothwell, Mion, Zinn & Macpeak 5 7 ABSTRACT A loud speaker is installedon the rear plane of a baffle board facing an opening within the baffleboard which opening in cross section takes the form of a narrowforwardly directed cone and an annular acoustic resistance member whichis triangular shaped in section is fixed to the cutting plane of theopening. Alternatively, a ring member which narrows in a forwarddirection to form a forwardly narrowing cone in cross section is fixedto the front of a loud speaker flange Y and fits within a baffle boardopening with the flange installed on-the rear plane of the baffle board.An annular acoustic resistance member of triangular cross section isfixed to the inside surface of the forwardly narrowing ring or to thefront surface of the loud speaker flange internally of the ring.

6 Claims, 4 Drawing Figures LOUD SPEAKER SYSTEM BACKGROUND OF THEINVENTION th e same protrudes forwardlyof the loud speaker installingflanges.

2. Description of the Prior Art When dome-type loud speakers, or similarloud speakers whose front part protrudes forwardly of the installingflanges, are installed within a loud speaker enclosure, if the speakeris installed on the front plane of a baffle board of the loud speakerenclosure, it is impossible to properly decorate the same by means of asaran net panel by stretching the netacross-"the baffle board due to theprotruding portion of the loud speaker. On the contrary, as' shown inFIGS. 2A and 2B, loud speakers .of this type may be readily installedonthe rear of the baffle board with the protruding portion projectingwithin an opening formed within the baffle board. However, if theopening of the illustratedbaffle board 1 is cut such that the wallsdefining the opening are at right angles to the plane of the board, theacoustic characteristics of the loud speaker system are adverselyaffected by cavity phenomena and reflection phenomena which occur in theopening. Even where the opening is in the shape of a cone which widensin the forward direction as shown in FIG. 2B, interference betweenemitted sound and reflected sound cannot be avoided.

SUMMARY OF THE INVENTION The present invention takes notice of theafore-mentioned problems. It is one object of the present invention toprovide a loud speaker system with means for reducing the influence ofcavity phenomena andreflection phenomena occurring within an opening ofa baffle board and thereby improving the acoustic characteristics of aloud speaker system.

It is another object of the-present invention to provide' a loud speakersystem in which the opening of the baffle boardis in the form, in crosssection, of a narrowing cone in a forward direction and wherein anannular acoustic resistance member of triangular shape in cross sectionand being formed of sponge or rubber, is fixed to the cutting plane ofthe opening.

It is a further object of the present invention to provide a loudspeaker system in which a ring member narrows in a forward direction toform, in cross section, a

forwardly'narrowing cone and is arranged on the flange of the loudspeaker permitting the loud speaker to be fixed in position within anopening of a baffle board, with an annular acoustic resistance member,shaped triangularly in cross section and formed of sponge or rubbermaterial, being fixed either to the inside surface of the ring member orto the flange just inside the ring member.

Other objects, advantages and features of the present invention willbecome apparent from the following description taken. in conjunctionwith the accompanying drawings. 1

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are principal,sectional views of two embodiments of loud speaker systems in accordancewith the present invention.

FIGS. 2A and 2B are principal, sectional views of two prior art loudspeaker systems.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1A illustrates oneembodiment of this invention. A baffle board 3 is provided with acircular opening 31 which is so shaped as to define a forwardlynarrowing cone. An acoustic resistance 4 which is annular in form, is oftriangular shape in cross section and may be formed of sponge or rubbermaterial with the acoustic resistance member 4 being fixed to the baffleboard on the cutting plane 31A. A middle or high range loud speaker 5such as a dome type loud speaker is installed on the baffle board 3with'screws 6,.such that the dome projects within the opening 31'.Alternatively, a multi-cellular horn type loud speaker may be installedtherein.

Consequently, a portion of the sound emitted fro the loud speaker 5 isreflected first by the cutting plane 31A of the baffle board 3andsecondly by flange 51 of the loud speaker 5 passing through theacoustic resistance member 4 and the reflected sound is then emittedoutwardly. Since the reflected sound is sufficiently reduced by thecapacity through the acoustic resistance member 4, the direct soundemitted from the loud speaker 5 through the opening and the reflectedsound would not substantially interfere with each other. Further,because of the buffer effect of the acoustic resistance member 4, acavity phenomena occurs in the opening 31 which scarcely disturbs theacoustic characteristics of the speaker system.

Moreover, since the opening 31. is conical in shape, a standing wavetrain is hardly set up within this opening.

FIG. 1B shows another embodiment of this invention. The same elementsshown in this Figures, as shown in FIG. 1A, carry the same numericaldesignations. In the loud speaker system illustrated in FIG. 18, a solidring member 7 tapers inwardly in a forward direction to define a narrowcone in cross section, and is arranged on the flange 51 of the loudspeaker 5 and operates in the same manner as the cutting plane of thebaffle board 3 of the first embodiment which also narrows in a conicalforward manner. An acoustic resistance member 4 is fixed to the insidesurface of ring member 6 in similar fashion to the previous embodiment.Alternatively, the resistance member 4 may be fixed to the flange 51internally of the ring member 6.

What is claimed is:

1. In a loud speaker system comprising a baffle board having an openingtherein and a loud speaker installed on the rear surface of the boardand spanning said opening, the improvement wherein:

loud speaker to absorb soundsreflected from said 7 plane.

2. The loud speaker system as claimed in claim 1, wherein said openingis defined by a cutting plane within said baffle board inclined inwardlyin the direction of emitted sound and said hollow acoustic resistancemember lines said cutting plane and faces said loud speaker.

3. The loud speaker system as claimed in claim 2, wherein said acousticresistance member is triangular shaped in cross section.

4. The loud speaker system as claimed in claim 3, wherein said openingis circular, and said hollow acoustic resistance member is annular.

5. The loud speaker system as claimed in claim 1, wherein saidreflecting plane is formed by a ring member narrowing in the directionof emitted sound, said loud speaker ismounted to said baffle board by aflange, said ring member is fixed to the front surface of said flangewithin said opening, and said acoustic resistance member is fixed to theinsidesurface of said ring member. 7

6. The loud speaker system as claimed in claim 1, wherein said loudspeaker is installed on the rear surface of said baffle board bya-flange member, a ring member is positioned within said opening andtapers inwardly in the direction of emitted sound, is fixed to theflange member on the front surface of the same, and an acousticresistance member is annular in form, triangular shaped in cross sectionand is fixed to the surface of one of said members and positionedbetween the inside surface of said ring member and the front surface ofsaid flange member.

i I i

1. In a loud speaker system comprising a baffle board having an openingtherein and a loud speaker installed on the rear surface of the boardand spanning said opening, the improvement wherein: said openingincludes means defining a sound reflecting plane inclined inwardly inthe direction of emitted sound, and wherein a hollow acoustic resistancemember lines said plane and faces said loud speaker to absorb soundsreflected from said plane.
 2. The loud speaker system as claimed inclaim 1, wherein said opening is defined by a cutting plane within saidbaffle board inclined inwardly in the direction of emitted sound andsaid hollow acoustic resistance member lines said cutting plane andfaces said loud speaker.
 3. The loud speaker system as claimed in claim2, wherein said acoustic resistance member is triangular shaped in crosssection.
 4. The loud speaker system as claimed in claim 3, wherein saidopening is circular, and said hollow acoustic resistance member isannular.
 5. The loud speaker system as claimed in claim 1, wherein saidreflecting plane is formed by a ring member narrowing in the directionof emitted sound, said loud speaker is mounted to said baffle board by aflange, said ring member is fixed to the front surface of said flangewithin said opening, and said acoustic resistance member is fixed to theinside surface of said ring member.
 6. The loud speaker system asclaimed in claim 1, wherein said loud speaker is installed on the rearsurface of said baffle board by a flange member, a ring member ispositioned within said opening and tapers inwardly in the direction ofemitted sound, is fixed to the flange member on the front surface of thesame, and an acoustic resistance member is annular in form, triangularshaped in cross section and is fixed to the surface of one of saidmembers and positioned between the inside surface of said ring memberand the front surface of said flange member.